EQ1: Drainage Basins

Question 1

What type of system is a drainage basin

Answer 1

• it’s an open system as there are external jnputs and outputs causing the amount of water in a basin to change

Question 2

Define saturation point

Answer 2

The temperature to which air must be cooled to become saturated with water vapour

Question 3

What is meant by ‘100 percent humidity’

Answer 3

Air holds as much water vapour as it can at the given temperature

Question 4

What is meant by ‘dew point’

Answer 4

The temperature at which dew forms, it is a measure of atmospheric pressure

Question 5

What conditions are needed for precipitation to form

Answer 5

1 - air needs to be cooled to saturation point with relative humidity at 100 percent

2 - condensation nuclei, such as dust, to facilitate the growth of water droplets in clouds

3 - a temperature below dew point

Question 6

What is a rain shadow

Answer 6

• A region having little rainfall because it is sheltered by prevailing winds by a range of hills

Question 7

Give two example of human activities influencing drainage basins

Answer 7

1 - deforestation = decreasing evapotranspiration and increase in surface run-off

2 - cloud seeding = the use of ammonium nitrate which acts as a condensation nucleus forming clouds and therefore attracting water droplets